Today, bankers and traders sit at the top of the food chain — the carnivores of the system, devouring everyone and everything below. Near the bottom toils the farmer. For him, the rising price of grain should have been a windfall, but speculation has also created spikes in everything the farmer must buy to grow his grain — from seed to fertilizer to diesel fuel. At the very bottom lies the consumer. The average American, who spends roughly 8 to 12 percent of her weekly paycheck on food, did not immediately feel the crunch of rising costs. But for the roughly 2-billion people across the world who spend more than 50 percent of their income on food, the effects have been staggering: 250 million people joined the ranks of the hungry in 2008, bringing the total of the world’s “food insecure” to a peak of 1 billion — a number never seen before.